Method and apparatus for sound producing



oa. 3o 1 92s. 1,689,574

R. L, WILLIAMS METHOD ND APPARA"r'Us Fon SOUND PRovucING Filed Dec. 1l, 1924 `:5 Sheets-Sheet 1 Oct. 3o, lsza 1,689,574

l R. L. WILLIAMS METHOD AND APPARATUS FOR SOUND PRODUCING Filed Dec. 11, 1924 s sheets-sheet 2 a6 ,A A O v I mien for: @abe/" L IWW/ams.

R. L. WILLIAMS METHO AND APPARATUS FOR SOUND PRODUCING Oct. 30, 1928. 1,689,574

Filed Dec. 11, 1924 5 Sheets-Sheet 3 IN V EN TOR. Ebbe/' L. Williams ATTORNE Patented Oct. 30, 1928.

UNITED stares N insane.

PATENT FFEQF..

ROBERT LONGFELLOW WILLIAMS, OF NEWTON, MASSACHUSETTS, ASSIGNOR TO SUB- IARINE SIGNAL CORPORATION, 0F BOSTON, MASSACHUSETTS, A CORE'ORATION 0F DELAWARE.

METHOD AND APPARATUS FOR SOUND ERODUGING.

Application led December 11', 1924. Serial No. 755,291.

The present invention is concerned in particular with the production of sound waves in water or other compressional medium in which it is desirable to impart into the water a sound impulse of high power.

In the present case I accomplish the desired result with an electromagnetic sound impact device in which the energy is stored over a comparatively longer period ot time than the time necessary for imparting the energy to the sound radiating means.

In the particular embodiment described below an electromagnetic solenoid works against the action o' a spring which', in its normal position, exerts no pressure at all.. When the solenoid draws the striker against the pressure of the spring a definite amount of energy is converted into potential energy in the springwhich is transformed into kinetic energy so that it may be imparted in a very short space ot' time into the wat-er.

The purpose of the present invention is to obtain a device which will transmit a great amount of energy into the medium with a small power source.

A further purpose is to obtain a sound producer capable of producing a short note.

A further purpose is to obtain a sound producer capable of operating either under a direct or alternating current source.

It is moreover also the obj ect of the present invention to operate the sounding device with a minimum amount of sparking at the contact. The operation of the device may also be synchronized with a definite position of an indicator so that the sound is emitted ata predetermined definite time.

Further purposes and objects of the present invention will be learned from the ollowing description and drawing in which:

Figure l represents across section of the sounder.

Figure 2 a plan view of the device as shown in Figure l, and Figure 3 shows diagrammatically the method of operating the sounder.

Figure 4 shows a diagrammatic represen tation of the circuit and method o'l operating the sounder synchronously with the timing device.

In Figure l a diaphragm l is bolted to a casing 2 by means of the bolts 3 extending around the outer dang-e 4. In the circumference within the bolt circle are packing means consisting ot a groove 5 iilled with pack- `ing` and an embossed rim 6 fitting into the casing is a solenoid coil 14 which is held irnil ly in place by aI plate l5 of magnetic material by means of machine screws 16. To t-he upper part of the casing is screwed a cylindrical .A

iron piece 17 by means of the threaded portio-n 18, which screws into a tap in the top of the casing.

The plunger 19 works within the solenoid coil 14- in a sleeve 2O of composition which is slotted at 21 vertically to keep down eddy currents in the sleeve itself. @ne end of the sleeve rests against a shoulder of the cylindrical piece 17 and makes a close fit about that piece while the opposite end of the sleeve has a collar 22 of magnetic material litting closely about it and supported by a press lit in the piece l5. In the plunger 19 are grooves 23 which are filled with felt soaked in oil to lubricate the plunger in its' movement in the sleeve. rlhe plunger as shown in Figure l is in the position when no current is flowing through the solenoid. In this position t-he plunger rests against spring fingers 24 which are supported by a ring 25, the latter ring being 'fastened to the casing el. by screws 26. The lower Vpart of the plunger i9 has a boss 27 which is slightly convex on its striking surface 28, and which forms a shoulder 29 upon which rests the bearing plate 30 for the spring 31 to rest upon. The end ot the spring 31 is tapered to compensate for the pitch so that it rests fairly snugly in the corner 32 of the bearing plate 30. The upper part of the' spring 31 passes outside the collar 22 and rests in a corner formed by a boss in the plate 15 and a slight enlargement in the collar 22.

An air passage communicates through the plunger 19 as shown by 34 from the air space in the lower part of the striker into the air space 35 above the plunger. lvVhen the plunger is drawn upwards this air has a chance to escape into the lower chamber and when the plunger travels downward this space is again filled with air through the passage 34.

The protector 36 above the spring fingers 24 which is fastened to the casing by the screws 26 serves both to dampen the spring and to limit its upward motion.

An explanation of the operation of the sounding device is given in the following:

When direct or alternating current is sent through the leads 12 int-o the solenoid coil a force is exerted upon the plunger 19 tending to make it include as many lines of :torce as possible. The -magnetic path ot the 'flux threads through the center oi the coil, the lower plate 15, the cylindrical part of the outside casing 7, the top oi the casing 7 through the cylindrical piece 17 which may be called a stop, through the center ot the coil thus com pleting the path. The plunger will be drawn upwards it suliicient current is supplied to the coil so that the path of the flux is practically entirely through magnetic material in this latter position. rllhe plunger will strike against the leather washer 37 attached by the machine screw 38 to the surface 39 of the piece 17. Through this action the spring 31 is compressed and energy is stored in the spring. When the current is broken the force offthe spring drives the plunger downward transforming the energy stored up into the kinetic energy of the moving mass. The plunger bears down upon the spring fingers 24 which have little ei'lect in retarding the plunger and imparts a tremendous impact to the diaphragm 1 as it strikes the raised center part 40 of the diaphragm. At the end of the stroke the spring is entirely expanded so that the only pressure exerted upon the plunger is the rebound oi' the diaphragm 1 and the pressure due to the spring lingers 24. The spring fingers 24 are designed to aid in raising the plunger clear from the diaphragm so that the latter may be allowed to vibrate at lts own natural period and also to prevent the plunger from striking the diaphragm upon the rebound so that only one impact is given y to the diaphragm.

In the plan view shown in Figure 2 the easing is shown reinforced by ribs 41 thus furnishing a rigid surface against which the diaphragm is clamped.

In Figure 3 is shown the method of operating the sounder in connection with a synchronizing device. The cable 12 from the sounder comprises leads 41 and 42. Lead 41 connects the one potential of a source ot current through a resistance 43 and an ammeter A. The other potential lead 44 has resistances 4o, 46, 47 in series connecting to one side of a switch 49 operated by a rotating cam 56. Shunted across the leads 42 to 44 are switches 50, 51, 52; 50 before resistance 45; 51 before resistance 46; 52 before resistance 47 g in such a manner that when closed, 50 will cut out all the above three resistances, 51 resistances 46 and 47, and 52 resistance 47. The lead 42 connects to the switch 49 so that when all three switches 50, 51, and 52 are open and also 49, the current to the device is broken.

The closing of the current is accomplished when the cam 53 relieves the switch blade of switch 50. The current then Elowing through the solenoid raises the plunger. The first contact to be opened is by the cam 53 which thereby cuts resistance 45 in series with the solenoid and thereby decreases the current. yVhen cam 54 opens contact 51 the current is cut down still 'further by resistance 95 46. A similar reduction in current takes place when resistance 47 is thrown in circuit by the opening ot switch 52 by the act-ion of the cam 55. Since the current is new decreased to a minimum, there will be very little 1W' energy in the n'lagnetic field which must be absorbed to break the circuit. In this way the break can be made to take place at just the time it is desired, since there will be. very little areing thus insuring that the break is practically instantaneous.

At the time cam 55 comes under switch 52 all the switches but 49 are open. The cam 56 which opens the switch 49 travels on the disc 48 which makes ten revolutions to one of the 11H larger cam wheel 57. The disc 48 is synchronized with the desired mechanism in conj uncl tion with which it is to operate with the result that sometime during the interval when cam 55 holds open switch 52 the current is 115 suddenly broken and the plunger is released. Since the disc 48 revolves faster than the yother cam wheel the timing of the opening ol' the circuit may be accurately regulated. If the disc 48 is run in synchronism with a 12 time recording` device so that the opening of the switch 49 occurs at the zero point of the timing device, then the circuit will only be broken at the time when switch 49 and all the other switches are open. In this way an arcu- 12a ate synchronism ot' the sounder with the timing device is obtained.

Figure 4 shows the method of synchroniz ing the operation of the sounder with the timing device, as mentioned above. The indi- 13o CAB cating mark 61 on the cam wheel 55, shown in the iigure, points to the zero of the scale 69. The cams 53, 54 and 55 are shown in the position of maintaining open the contacts 50, 51 and 52 respectively. The cam 56 is shown opening the contacts 49 so that, as shown in the figure, the sounder 12 is being operated. The cams 53, 54 and 55 are lined rigidly on the shaft 64, which also carries a gear 62 meshing with gear 63, which is carried on the shaft 65 and which operates the cam wheel 48. As mentioned above the ratio of the synchronizing mechanism is ten to one, so that the shaft 65 makes ten revolutions to one of the shaft 64. As the arrow 61 comes to the zero of the scale the cam 56 opens rapidly the contacts 49, thus completing the opening of the sounder circuit, since the contacts 50, 51 and 52 are already open. In this manner the position of the arrow 61 can be accurately synchronized with the sounding of the sounder 12, since the contacts 49 are opened so much more rapidly than the other contacts on the slower cams.

While it has always been desirable to use a device such as is described in the present application for submarine sounding', yet it has been found diicult to operate such a soun der successfully because of the inherent inaccuracy in trying to operate the sounder synchronously with a timing device. The present method and apparatus employed have been found successful in operating the impact sounder, due t0 the very slight amount of current which is broken by the last cam,

l here cam 49, and also because of the rapidity with which the current is broken.

From the above ,description is will be noticed that the switch 49 opens ten times to each time the other switches open but that there will be only one operation of the sounder among these ten openings of switch 49. Therefore, it is evident that with the present device the more rapid operating synchronizing switch controls the sounding device but only once in every ten times of its operation. Due to the fact that the switch 49 operates so much quicker than the other switches the error of operation due to the back lash of the gears in a slow system is avoided while the rapid action on account of the speed of the disc wheel 48, and other features cause the timing of the opening of the contacts and the operation of the sounder to be very accurate.

Having now described my invention I claim:

1. In an electromagnetic sounding system, an electromagnetic sound generator of the impact type, an electrical source of energy, a switching mechanism controlling the transfer of energy from the electrical source to the generator, comprising a switching means, means controlled by said switching means for reducing the current suppliedto the sound generator, and a second switching means for breaking the current at a time when the current has been reduced.

2. In an electromagnetic sounding system, a switching system for controlling the operation of a sound generator comprising switching means operating at a comparatively s low period to open one branch of a shunt circuit, a second switching means operating at a more rapid period than the first to complete the opening of the circuit, whereby the more rapidly operating switching means controls the operation of the system at 'times when the iirst branch of the shunt circuit is open.

3. In an electromagnetic sounding system, an electromagnetic sound generator of the impact type, an electrical source of energy, a switching mechanism controlling the transfer of energy from the electrical source to the generator, comprising a switching means, means for operating said switching means periodically, means controlled by said switching means for reducing the current supplied to the sound generator, a second s witchin means, and means for operating said secon switching means periodically, but at axmore rapid rate than said first switching means for breaking the current at a time when the current has becn'reduced.

4. An electric sound generating system of the impact type comprising an electric sound generator, a scale, an indicator adapted to move with reference to the scale and means for producing the sound when the indicator has reached a desired position with reference to the scale, comprising means for energizing the sound producing mechanism prior to the production of the sound, means for reducing the energy so sup lied, whereby the sounding mechanism is rea y to operate for the production of the sound, and means including in part said energizing means for releasing the sounding mechanism for the production 0f the sound, said means accurately synchronized. with the desired position of said indicator.

5. A sound generating system of the impact type comprising a scale, an indicator adapted to move with reference to the scale, and means for producing the sound when the indicator has reached a desired position with reference to the scale, comprising means for energizing and restraining the sound producing mechanism until said mechanism is completely energized, means for reducing the energy supplied to said means to the point where the mechanism is just restrained and means, including in part said energizing means, for releasing suddenly the restraining means at the moment when the indicator has reached the desired position with reference to the scale.

6. An electric sound generating system of the impact type comprising an impact memllO ber, a diaphragm on which said impact member operates, a restraining spring and electromagnetic means for retracting said impact member against said restraining means and means for controlling the supply of current to said electromagnetic means including means for decreasing the current sup lied to said electromagnetic means after sai iml pact member is in its retracted position and means for breaking the current and releasing said impact member after it has been reduced.

7. An electric sound enerating system comprising a scale, an indicator adapted to move with reference to the scale and a sound producer of .the impact type comprising an impact member, a diaphragm on v vhich said impact member operates, a restraining spring and electromagnetic means for retracting said impact member against said restraining means, means for controlling the supply of current to said electromagnetic means including means for decreasing the current supplied to said electromagnetic means after said impact member is in its retracted position and means for breaking the current and releasing said impact member after it has been reduced and when said indicator has reached a desired position With reference to the scale.

In testimony whereof I aiiiX my signature.

ROBERT LONGFELLOW WILLIAMS. 

